Also use lambda for sorting

src/main/java/com/owncloud/android/utils/FileSortOrderByDate.java

@@ -47,12 +47,9 @@ public class FileSortOrderByDate extends FileSortOrder {
     public List<OCFile> sortCloudFiles(List<OCFile> files) {
         final int multiplier = mAscending ? 1 : -1;
 
-        Collections.sort(files, new Comparator<OCFile>() {
-            @SuppressFBWarnings(value = "Bx", justification = "Would require stepping up API level")
-            public int compare(OCFile o1, OCFile o2) {
+        Collections.sort(files, (o1, o2) -> {
                 Long obj1 = o1.getModificationTimestamp();
                 return multiplier * obj1.compareTo(o2.getModificationTimestamp());
-            }
         });
 
         return super.sortCloudFiles(files);